The present invention relates to a dispenser for attaching abrasive sheets to a backup pad, and more particularly to a dispenser that conveniently aligns the vacuum holes in an abrasive sheet with the vacuum holes in the backup pad, as well as centering the abrasive sheet onto the backup pad.
Abrasives are commonly used to grind, sand, and polish materials such as wood, metal, paint, and plastic. One method of abrading a work piece is to affix an abrasive sheet to a backup pad, and to rotate the backup pad while urging the abrasive against a workpiece. In many applications, the abrasive sheet and the backup pad are circular, although other configurations are also known, For example, U.S. Pat. No. 4,920,702 (Kloss et al.) discloses a portable grinder having, in one embodiment, a generally triangular backup pad and abrasive sheet that are vibrated rather than rotated.
The abrasive sheet may be affixed to the backup pad in a number of different ways. For example, the use of a pressure sensitive adhesive (see e.g., U.S. Pat. No. 3,849,949 (Steinhauser et al.), interengaging fastener members, such as hook portions on the backup pad and loop fabric on the abrasive sheet (see e.g., U.S. Pat. No. 4,875,259 (Appeldorn) or U.S. Pat. No. 5,201,101 (Rouser et al.) and cooperating male and female fastener members, are known in the art.
The backup pad may be configured to be hand held, or may be configured for attachment to a powered abrading apparatus. A typical abrading apparatus includes a rotating output shaft that is powered by an abrading head. These abrading apparatuses, alternatively referred to as grinders herein, may be electrically or pneumatically powered, and typically rotate the backup pad at speeds between 3,000 and 20,000 revolutions per minute. The abrading apparatus may be one of several types. For example, a rotary grinder simply rotates the backup pad and attached abrasive sheet about a fixed axis. A random orbital grinder combines a rotary and orbital motion that results in a random motion of the backup pad with respect to the abrading head.
The abrading apparatus can also have dust collection holes incorporated into the backup pad. An abrasive sheet is then desired which also has vacuum holes. This system causes the dust to be drawn away from the abrading area through the vacuum holes. The abrading tool has an attached container in which the dust is collected or may be attached by hose to a separate dust collector.
The diameter of the abrasive sheet is typically larger than the diameter of the backup pad (for example, a 127 mm sheet and a 124 mm pad), to permit abrading near the periphery of the abrasive sheet without damage to the backup pad or to the surface being abraded. It is desirable to position the abrasive sheet relative to the backup pad so that the sheet extends beyond the backup pad around its entire circumference without any of the support of the backup pad exposed. It is also desirable to center the abrasive sheet relative to the backup pad so that the amount by which the sheet extends beyond the backup pad is relatively constant along the periphery of the sheet. In the case of a dust collection system the vacuum holes must be aligned as well in order for the dust to be extracted properly. Typically, the operator of the apparatus applies the abrasive sheet by hand while attempting to center it and align the vacuum holes as well as possible. It is also known to program robotic sanders to attach abrasive sheets centered on the backup pad (see U.S. Pat. No. 5,377,455 (Lanzer)).
In the case of through the pad dust extraction, the abrading tool is turned over to expose the backup pad. The vacuum holes of an abrasive sheet are then visually lined up with the vacuum holes of the backup pad. The tool is then turned right side up for continued use.
Various dispensers for abrasive articles are known, such as those disclosed in U.S. Pat. No. 3,849,949 (Steinhauser et. Al.), WIPO International Patent Application Publication No. WO96/38264 (King et al.) and U.S. Pat. No. 6,193,337 (Roeker, et al.) However, these dispensers do not provide a way to align the vacuum holes in abrasive sheets with the vacuum holes in a backup pad.
It is desirable to provide an abrasive sheet dispenser that simply, quickly and effectively centers and aligns vacuum hole abrasive sheets onto a vacuum hole backup pad.